Wi-Fi is a trade name for a wireless local area network (WLAN) that uses one of the IEEE 802.11 standards. It is a trademark of the Wi-Fi Alliance. Individual homes and businesses often use Wi-Fi to connect laptops and smart phones to the Internet. Wi-Fi Hotspots may be found in coffee shops and various other public establishments. Wi-Fi is used to create campus-wide and city-wide wireless networks.
Wi-Fi networks are built using one or more wireless routers called access points. “Ad hoc” computer to computer Wi-Fi networks are also possible. The Wi-Fi network is connected to the larger Internet using DSL, cable modem, and other Internet access technologies. Data rates range from 6 to 600 Mbit/s. Wi-Fi service range is fairly short, typically 20 to 250 m or from 65 to 820 feet. Both data rate and range are quite variable depending on the Wi-Fi protocol, location, frequency, building construction, and interference from other devices. Using directional antennas and with careful engineering Wi-Fi can be extended to operate over distances of up to several km, see “Wireless ISP” below.
Wireless Internet service providers typically employ low-cost IEEE 802.11 Wi-Fi radio systems to link up remote locations over great distances (Long-range Wi-Fi), but may use other higher-power radio communications systems as well.
Traditional 802.11b is an unlicensed omnidirectional service designed to span between 100 and 150 m (300 to 500 ft). By focusing the radio signal using a directional antenna 802.11b can operate reliably over a distance of many km(miles), although the technology’s line-of-sight requirements hamper connectivity in areas with hilly or heavily foliated terrain. In addition, compared to hard-wired connectivity, there are security risks (unless robust security protocols are enabled); data rates are significantly slower (2 to 50 times slower); and the network can be less stable, due to interference from other wireless devices and networks, weather and line-of-sight problems.
Rural wireless-ISP installations are typically not commercial in nature and are instead a patchwork of systems built up by hobbyists mounting antennas on radio masts and towers, agricultural storage silos, very tall trees, or whatever other tall objects are available. There are currently a number of companies that provide this service.
Motorola Canopy and other proprietary technologies offer wireless access to rural and other markets that are hard to reach using Wi-Fi or WiMAX.
Worldwide Interoperability for Microwave Access (WiMAX ) is a set of interoperable implementations of the IEEE 802.16 family of wireless-network standards certified by the WiMAX Forum. WiMAX enables “the delivery of last mile wireless broadband access as an alternative to cable and DSL”. The original IEEE 802.16 standard, now called “Fixed WiMAX”, was published in 2001 and provided 30 to 40 megabit-per-second data rates. Mobility support was added in 2005. A 2011 update provides data rates up to 1 Gbit/s for fixed stations. WiMax offers a metropolitan area network with a signal radius of about 50 km (30 miles), far surpassing the 30-metre (100-foot) wireless range of a conventional Wi-Fi local area network (LAN). WiMAX signals also penetrate building walls much more effectively than Wi-Fi.
Satellite Internet access via VSAT in Ghana
Satellite Internet service provides fixed, portable, and mobile Internet access. It is among the most expensive forms of broadband Internet access, but may be the only choice available in remote areas. Data rates range from 2 kbit/s to 1 Gbit/s downstream and from 2 kbit/s to 10 Mbit/s upstream. Satellite communication typically requires a clear line of sight, will not work well through trees and other vegetation, is adversely affected by moisture, rain, and snow (known as rain fade), and may require a fairly large, carefully aimed, directional antenna.
Satellites in geostationary Earth orbit (GEO) operate in a fixed position 35,786 km (22,236 miles) above the earth’s equator. Even at the speed of light (about 300,000 km/s or 186,000 miles per second), it takes a quarter of a second for a radio signal to travel from the earth to the satellite and back. When other switching and routing delays are added and the delays are doubled to allow for a full round-trip transmission, the total delay can be 0.75 to 1.25 seconds. This latency is large when compared to other forms of Internet access with typical latencies that range from 0.015 to 0.2 seconds. Long latencies can make some applications, such as video conferencing, voice over IP, multiplayer games, and remote control of equipment, that require a real-time response impracticable via satellite. TCP tuning and TCP acceleration techniques can mitigate some of these problems. GEO satellites do not cover the earth’s polar regions. HughesNet and ViaSat are GEO systems.
Satellites in Low Earth orbit (LEO, below 2000 km or 1243 miles) and Medium earth orbit (MEO, between 2000 and 35,786 km or 1,243 and 22,236 miles) are less common, operate at lower altitudes, and are not fixed in their position above the earth. Lower altitudes allow lower latencies and make real-time interactive Internet applications feasible. LEO systems include Globalstar and Iridium. The O3b Satellite Constellation is a proposed MEO system with a latency of 125 ms. COMMStellation™ is a LEO system, scheduled for launch in 2015, that is expected to have a latency of just 7 ms..
Service mark for GSMA
Mobile broadband is the marketing term for wireless Internet access delivered through mobile phone towers to computers, mobile phones (called “cell phones” in North America and South Africa), and other digital devices using portable modems. Some mobile services allow more than one device to be connected to the Internet using a single cellular connection using a process called tethering. The modem may be built into laptop computers, tablets, mobile phones, and other devices, added to some devices using PC cards, USB modems, and USB sticks or dongles, or separate wireless modems can be used.
New mobile phone technology and infrastructure is introduced periodically and generally involves a change in the fundamental nature of the service, non-backwards-compatible transmission technology, higher peak data rates, new frequency bands, wider channel frequency bandwidth in Hertz becomes available. These transitions are referred to as generations. The first mobile data services became available during the second generation (2G)
The download (to the user) and upload (to the Internet) data rates given above are peak or maximum rates and end users will typically experience lower data rates.
WiMAX was originally developed to deliver fixed wireless service with wireless mobility added in 2005. CDPD, CDMA2000 EV-DO, and MBWA are no longer being actively developed.
In 2011, 90% of the world’s population lived in areas with 2G coverage, while 45% lived in areas with 2G and 3G coverage.
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